Recovery of solids from industrial wastes



Aug. 11, 1942.

E. C. PATTEE l RECOVERY oF soLIDs FROM IVNDUSTRIAL-,wAsTEs' 'Filed Dec. 17, 1958 ZvSheets-Sheet 1 INVENTOR ATTORNEYS Patented Aug-.11,1942

UNITED*-sTATEs,-j PATENT OFFICE l -nacovnny or scvngglqzou mpUs'rnrAL Ems emule rame, cimmed-omo, signor zo f invention relates to'a process for there-k coveryvof solids from distillery slop, spent beer,

= plantwssteand othersimnar industrial waste liquids vwhich contain valuable solids in suspension and in solution. Y

- v.Alcohol distilleries andl similar plants have 'always been confronted with the problem of the recoveryl of valuable material in the disposal of., their waste. residues,A commonly -termed spent beer or fstill slop. One of the chief problems has been to devise a means to recover'the .valuable solids'from the slop at va. cost sumciently low'to permit'of proiitable operation. The great majority `of the vprocesses so far devised or used have been found too expensive to be practical or proiitable.V I' The -same problem which has coni fronted alcohol distilleries, has also been a serious one. facing other industries, such as 'canning plants having vwaste liquids, especially'wher'e the waste liquids in addition to having `solidsin solution 'also containinsoluble solids in suspension.

In distillery slop the insoluble solids in 'suspenf sionin the liquid vary greatly in size ranging `from microscopic particles such as ye'ast cells to large grain hulls about-one quarter of an inch in length. For this reason and due to the nature of the slop, which is generally foamy and dense, it

- thickener II where it is allowed to form a sedi- Q has been'extremely difllcult to 'separate the col loidalproteins held in suspension from the water.

solution.

The solids which occur in the distillery slop,

or plant waste, contain valuable food elements,

including fiber, protein', oil, yeast, and soluble carbohydrates.V If these solids can berecov-` ered economically andpractically, they maybe manufactured into food products with high nutritive value.

This type of food product has been- National Distillers Products Corporation, New

York, N. Y., a corporation of Virginia'.

:application December 417, 193s, 246,339

' y. sclaims.V v screened, but it is very diillcult 'to economically and practically. separate the fine colloidal proings, in which: Y v Figure 1 is, a ilow diagram of apparatusused in Vcarrying out the procesa. and Figures 2,.3

and 4 are similar diagrams showingsmodiflcations of parts of. the apparatus.

In this process the slop from the dealcoholiz-f A. ing stills is stored in a tank Il and from'thetank the slop is pumped to a-settling tank or ment. When the` insoluble solids have settled to a slurry, a relatively clear supernatant liquor tank 4II is then taken 'on through a pipe- Iland carried to a centrifuge Il, whichmay be either of the batch or continuous-type. '.Inv the cen- I trifuge the solids are separated from the excess' liquid which is discharged at IE' and returned, through -a conduit I1, tothe settling tank for Vfurther clarification. After leaving the-centrifuge, the solids passv to a lter or mechanical press IS where part of the remaining liquid is expressed from it. The liquid 4squeezed from the' cake inthe lter press is returned to the settling tank with the liquid discharged fromthe centrifuge.

. The supernatant liquor containing the soluble found especially satisfactory for use as a cattle' The new process of this invention maybe ,ad-jV vantageouslyy employed .in the recovery ofsolidsv both in suspension and in solution in many difsolids is carried from the launderA I2 by the conduit l,I8 tothe vthin slop tank I! where it is- -stored. From the bottom of the ,thin slop tank the' liquor is drawn through a pipe l2l to bev either further processed or run to the sewer for disposal. When'the liquorv is to be further processed it is pipedto a series of evaporators IIA. IIB, IIC and ZID. These evaporators having the usual heating tubes, heated by steam, are

ferent types lof wastenliquids. For .purposes of Y Y -description'i ,l'iere.- vthe new process will be conlsidered in connection with the recovery of solids from distillery slop., although it; is equally vapplicable to other like industrial wastefliquids.' The 'slop as it vcomes from the de'alcoholizing still Y containsv both -soluble and insoluble materials.v The insoluble -solids are Agenerally presentv inV particle sizes ranging vfromcoarse grain hulls arranged in a battery so that the liquid from the Il enters evaporatorIIB and' from. there is'forced to evaporator IIC, then to 2ID,5. 8nd

- from there. to evaporator IIA. Pumps inthe downitouiinev colloidal proteins, and the latter are usually in suspension. The coarse grain hulls do not present any great problem in their sepa.- j

ration from the solution since they may be easilyl to conduits leading into the battery of evaporators cause a forced circulation inwhich-the liquor is,-

pumped through the heating tubes ofthe evaporators 'at a velocity of greater than iive linear feet per. second. Under forced circulation the evaporator tubes will not foul easily, and ithas been foundthat the evaporators will remain clean for long periods. The concentratedevaporator discharge, generally in the form of a syrup,

' is then carried from the evaporator 2 IA by a pipe while in the conveyor or in the dryer.

22 to an evaporator syrup tank 23 where the syrup is stored.

Froml the tank 23 the syrup ows through a pipe 24 to a mixing conveyor 25 where it is mixed with the'press cake being carried from the press Il. In the mixing conveyor the press cake and the syrup may bev mixed with suiiicient pr'evious-V ly dried material from a storage bin ently described, -to prevent caking or balling The mixture from the mixing conveyor is carried to a drier 2l by another conveyor 21, and from the drier a conveyor 28 carries the-dried material to a bin 2l where itis stored and further treated.- Where it may be desired to add dried material to the mixture in the conveyor 25, such dried' material is carried from the bin-29 by the pipe 30 to the conveyor. 'I'he bulk of the driedmaterial is carried oiI from the bin by conveyor 3l for storage use or further processing., as may be desired.

to be pres-A the pipe tothe boiler. In order to provide rapid passage of the solution through the heating tubes, a pump 53 is installed, and it has been found advantageous to pass the liquid through the tubes at a linear velocity of greater than live feet per second. From the boiler, the liquid passes successively to the evaporators 2IC, 2ID, and ZIA. Similar results cauv be obtained in large bodied vessels heated by ame or combustion gases, when the liquid having solids in solution is vigorously agitated over the surface. It

-will be obvious that the type oi boiler employed in the step may be lvaried, and that shown in Fig- In somecases, wherethe solid particles in su'so pension are large o r whereit is otherwise desir` able, the spent beer may be carried from the still slop storage tank III to ascreen 33 shown in Figure 2, which may be interposed betweenthe stor-,I age tank I0 andfthe settling tank II, or take the piace of the settling tank. In the latter case the rough screenings are carried directly to the iilter press I6 by a' pipe 34 and the screened liquid slop isvcarried to the centrifuge Il .by a pipe v351er further treatment, as has been outlined above. In such a case the'solids from the centri-1 fuge and the screenings are mixed in the nlter or mechanicalpress Ahopper and the resulting` mixture is deliqueiied in the press I8.,

liquor from'the settling tank.` Due to the enormous amounts of steam necessary, the use of evaporators. is expensive and it has been found in some instances that a more economicalv recov-y ery of the soluble solids from this liquid may be obtained by the substitution ,of a boiler in place of `of liquors'to use steam as the source of heat in a multiple 'effect evaporator, andas thisrequires theevaporation of enormous quantities of water, the cost of evaporation is very high in re ure 3 is only for the purpose of illustration.V

In many; cases it has been toimd that the proc- "ess for the recovery of the solids will operate more elciently by the substitution oi a iilter for the centrifuge and the mechanical press. SuchV an arrangement is illustrated in Figure 4. 'I'he 20 distillery slop from4 the storage tank Il is carried to the settling tank lII where the insoluble solids are allowed to,l settle and form a slurry in the bottom of the settling tank. From the settling tank II, the slurry is carried toa iilter 6U. The filtrate from which the slurry has been precipitated isreturned to the settling tank by a conduit 6I to be there treated again, which slurry is carried from the filter $0 to a mixer 62 where it is mixed with the evaporator syrup in the same way as described in connection with Figures 1, 2, and 3. The liquid containing the soluble material is taken of! from the upper part of the set- Y In vthe iiowdiagralril illustrated in Figure 1, a

battery oi evaporators `ZIA, 2IB, 2IC, 2ID are shown ,employed for concentrating the overilow4 40:

. liquid from which'substantially all of the insoiu- Y tling tank, and is treated in the same manner as has been previously outlined to evaporate oi! some of the moisture, and to form a syrup ofthe lsoluble solids.

This process has been found especially advantagous ,where the distillery slop settlesquickly, since' it eliminates a step in the concentration of the slurry.

While the process as outlined'above includes l the yrecovery of substantially all solids present in the distillery slop as one dry product, it may in some cases be desired to recover the solids as two Y or more products. For example, one of the products may consist of the insoluble solidswhich are present in still slop as-,coarse and colloidal substances, and such a product might be utilized in either the wetvordry state. 'Ihe coarse and colloidal substances generally contain high p'ercentages of protein, uber, oil and yeast. `The other product is soluble solids recovered from the v ble substances have beenseparated.- The dried lation to the value ofthe recovered products.

' in thisway the moisture in theliquids containing thesoluble solids is reduced by evaporation. 'The Axsteam from such evaporation may be employed in heating the remaining evaporators. Since there is a tendency o! thedissolved solids to pre- 'cipitaee or cake inthe tubes or the -beam-i1; has a been found advantageous to Acause the ow of the liquids to be rapid'and continuous. By the rapid iiow of the liquids through the tubes, the solids are prevented from caking or precipitating in the tubes or-in the boiler heatingsurfaces.

Figure 3 shows a boiler SII having the usual heating coils il and nre-box 52. The overow products from this solution generally contain high percentages of soluble carbohydrates and inorganic minerals. r

yIn the treatment of distillery slop, it is desirable in some cases to accelerate or promote the coagulation and settling of the fine colloidal Y. materlalsby the addition oi coasulants to the still slop whilefit is in the still slop storage tank.

Lime, sodium carbonategvie'rric sulfate, bentonite' and diatomaceousearthy have been found et*- iiquor having solids in solution passes through iicacious for the'pu'rpose.-

Some typesor distillery waste soluble solids will settle rapidly. In these cases the settling tank may be eliminated and the slop passed.directly from, thel slop storage .tank Il to the centrifuge Il'. The centritugecake then will be carried to iilterpress Il, and therearticles or slope 4have such physical characteristics that the infor this purpose.

tling tank, it is quite obvious that the time required can .be greatly reduced. In other cases where the distillery slops have such physical characteristics that the insoluble solids will filter rapidly, it has been found advantageous to carry the slurry from the settling tank II directly to the filter press and thus eliminate the centrii'uging step with consequent saving in time and energy.

The process of this invention has the additional advantage in that the time necessary for ployed to circulate the material through the variousparts of the apparatus. Since the materialwhich will be recovered may vary to a great extent, pumps of greater or small capacity may be' employed. Such pumps are illustrated on the flow-sheet by gures numbered 40, 4|', 42, 43, 44,

45, 46, 53, 63, 64, 65 and 6G. However, where it is necessary, additional pumps may beemployed to force the material through the apparatus at the desired 'speed of now. l

By the process of this invention the recovery of valuable materials from spent beer or-liquid lWaste products of distilleries and canning factories may -be quickly and easily obtained.- 'I'he average'distillery can recover suicient materials from its spent beer or slop by the use of this process to make it practical to install apparatus The process above outlined has the added advantage of disposing ofthe material which would otherwise be carried to the sewers and there becomea serious problem of disposition. In many localities where sewage disposal is an acute problem, the addition of large amounts of distillery slop having solids in-suspension and in solution would either necessitate the installation of additional sewage disposal equipment or tax lthe facilities there existent. With the employment of this process the waste material carried to the sewers is only a watery liquid andcan thus vbe disposed of easily.

1. The process of treating distillery slop and like industrial waste 'liquids containing recoverable solids in solution and .in suspension which of coarse grain materials contained therein, subjecting the liquid to sedimentation and decan- 'ing the solids of said slurry from the liquid part thereof, evaporating said supernatant liquor; and

cover the solids 'contained therein, and mixing the solids thus recovered by evaporation and the separated solids of said slurry.

comprises, screening the liquid for the removal the separated liquid part oi' said 'slurry to reable solids in solution and in suspension which comprises, subjecting the liquid to sedimentation and decantationto separate the suspended solids in the'formA of a slurry from a supernatant liq uor containing solids in solution, substantially separating the solid p art of said slurry from the liquid part thereof, circulating said supernatant liquor and the separated liquid part of said slurry Vthrough heated passages at a velocity greater than live linear feet per second for the eyaporation of the moisture andl the recovery of the solids contained therein, and mixing the solids thus recovered by evaporation and the .separated solid part of said slurry.

3. The process of treating distillery slop and vlike industrial waste liquids containing recoverable solids in solution and in suspension which comprises, subjecting the liquid to settling to separate the suspended solids in the form of a slurry from a supernatant liquor containing solids inY solution, ltering said slurry to substantially separate the liquid and the solid parts thereof, re-` turning the separated liquid part of said slurry for further settling-evaporation of the supernatant liquor to recover the solids contained therein, and mixing the solids thus recovered by evaporation with the separatedsolid'part of said slurry.

4. The process of treating distillery slops and like industrial waste liquids containing recoverable solids in solution and in suspension, which like industrial waste liquids containing recoverable solids in solution and in suspension which comprises subjecting the liquid to sedimentation and decantation to separate the suspended solidsv in the form of a slurry from a supernatant liquor containing solids in solution, `centrifuging said slurry to substantially separate the solid portions thereof from` the liquid portion, returning 'the separatedliquid portion of said slurry for further settling, evaporating said supernatant liquor to recover the solids contained therein, and mixing the. solids thus recovered by evaporation and the separated solids of said slurry.

6. The process of treating distillery slops and like industrial Waste liquids containing recoverable solids in solution'and in suspension which comprises subjecting vthe, liquid tosedimentation and decantation to separate the suspended solids in the form of a slurry from a supernatant liquor containing solids in solution, centrifuging said slurry to substantially separate the solid portions thereof from the liquid portion, returning the 'I separated liquid portion of said slurry for fur` ther settling, circulating said supernatant liquor through heated passages at a velocity greater than 5 linear feet per second for the evaporation of the moisture and the recovery of the solids contained therein, and mixing the solids thus recovered by evaporation and the separated solid 2. The process of treating distillery slop .and Dari? 0f -Said slurry. like industrial waste liquids containing recover- ELLIS CHARLES PA'rrEn 

